Method of and attachment for doped fabric



Oct. 4, 1949. w. w. LYSAK METHOD OF AND ATTACHMENT FOR DOPED FABRIC 2Sheets-Sheet l Filed May 25, 1945 .n nl E( 1 AGENT.

Oct. 4, 1949. w. w. LYSAK METHOD OF AND ATTACHMENT FOR DOPED FABRICl 2Sheets-Sheec 2 Filed may 25, 1945 INVENTOR Wa/erWLysaK AGENT PatentedOct. 4, 1949 METHOD F ANDATTACHMENT FRDPED Y FABRIC y Walter W. Ly-sak,Seymour', Conn., assigner to United,Aircraft Corporation, East Hartford,Conn., a corporation of Delaware:

Application Mayas, 1945,\Seriar No. 595,437:

inventionY relates' method for providing an improved cover for sectionsof aircraft. Morev particularly', this invention provides-'improved'means for covering an 'aircraft and freeing the outside cover fromirregular surfaces which increasey the drag -of' the aircraft, and!eliminating the need for tedious steps in'` the'fabrication-ofairfoilisections, for example.

' --In the ypast, it has beenV common practice to placeV the outsidecover upon-Y an airfoil` section and'- sew through the structural' partsof the section and thereafterp'lace a'V substance known as dopey on thefabric to shrink the same and glue the parte" together. All Vsurfacesthrough which lacings andstitches passedihad tape doped on over them inan attempt to streamline 'the same to reduce the" air"`fricti`on of thesurface. Such operations' failed to provide: completely smooth surfacesfor the'outer cover vof the air'- craftsection; and further calledV formanypreoise operationsin 4assembling the cover with respectto thebalance of the section'.

` An obiect of `the present invention is-to provide an improvedstructure including a smooth cover 'foraircraft A further ,objecty is toprovide an improved means and' method for covering airfoil sections thateliminatesv stitching` completely through structural parts.- when thecover is inl place.-

A' further; objectistoprovide meansfor covering4 an airfoil. sectionwhich will enable partial assembly, to be made` by the. fabricatorsbefore thedevice isnally assembled'.

Another object-in. keeping withfthe above.objects: to. provide. animproved; airfoilsection wherein` the tensionf of the cover underaerodynamic conditions; is taken-in shear. bydopedtogether surfaces and:tensionrin the threadsas1- sembling different parts:

A rfurther object,` in. keeping: with the above objects,` to. provideimproved covering means and method wherein the structural parteci? theaircraft section are strengthened by the parts making up means:tor'securingithe covervi'n place.

t further object, keeping with the Vaboveobject-snstoprovideimprovedmeanssandmethod for: `covering. airroil.sections in which. different structural. parts may bei braced. .totdifferent degrees by 'portions offthemeans forming the'coversecuremientl me ans.

f The foregoing andiA other fobj'ects will be either obvious or pointedout in the following specificatonandclaims. l

generally 'to means and 13 claims. (CL-ankles) Inline-drawings: Fig. 1'.isa perspective view with partsiinsection.. of assembled `part of an:aireraftrib and cover 'with the present means 'fori'securing the covertoithe'rib shown.

Fig. 2f-is an exploded view of partslof the cove securing means shownwith therib removed.

Fig. SssaA-diagrarnrnatie4 sectional view; similar to Fig. 1, butshowing the action of the securing means under aerodynamic'condit'ions.

Fig.. 4v is: a diagrammatic View of a modified form of my invention.

.Fig. '5-'is a viewof thaturnodincation shown in Fig-4 butwith thesecuring means shown inthe `position' -itf will ass-unie underaerodynamic conditions.

Fig; 6 is an exploded diagrammatic AView of' a modification ofthepresentinvention Vshow-ing a portion of the' securing means arranged forbracing theV flange of thev rib section.

- Fig. FIisa:diagrarnmaticview ofanother modi'- `cation of thepresentinvention.

In the following' description, some specicfembodiments off the presentinvention will be given; and some specilic steps in the fabrication ofthe device will `be explained. AItv will` be understood', however,thatfthose examples are Aonly illustrative of presently preferred formsof lconstruction and that many other constructions' can beV madekeeping-with theY teachings in the instant disclosure in view' ofthecurrentl knowledge of those skilledl in the art'. For that reason, Iwishnot to be', liinited only to those-forms shown and de'- sc'ribed butby' theiscope of theinvent-iony asdefined the claims setoutbelow.

In Fig. 1, fan airfoil'- section is' shown as'made up of a structuralmember, Yherein a ribcome prising a-web r|50v having flanges I 2extending laterally' of' the web; The Web ill is shown as made upoflaminated-construction suchas ply-Y Wood. 'The langes l2" are shown asbeing of solid wood and may alsoA be of plywood if de'- sired. However,fertile-purpose of practieing'the present" invention; itis notvnecessary that' the parts I0 and l2 be madeof wood, but could be madeof"meta1`, plastic or other suitable substance; The flanges I2' as shownin Fig. 1 will serve to increase the strength ofv theweb" l'. When thebottom part' of the airfoil section is thesameasthe top, the'entiresection' might take thefor'm of anI'beam, for example. However, othersectional-shapes :may be used without' departingfro'm the spirit of theinvention. n

A foundation strip r4 is cemented' or fsewed to the weblll: The Stripl4` entends aroundl the 3 members I2 and closely fits the web I0 and theflanges I2. A strip of metal foil I6 lies over the upper surface of thestrip I4. A suitable chemical substance such as Wax, for example, couldtake the place of the metal strip I6. The strip I6 is provided in theposition shown to prevent dope applied above the strip from seepingthrough and fastening parts, to be later described, to the upper flatsurface of the strip I4 adjacent the upper surfaces of the flanges I2. Afastening strip I8 lies over the strip I6 and may have substantially thesame area as the area of the upper surfaces of flanges I2. The fasteningstrip I8 is sewed to the foundation -strip I4 by stitches 20. A cover 22for the entire portion `of the aircraft to be assembled lies inengagement with the fastening strip I8. In the position thus assembled,dope 24 is applied to the surface of the cover fabric 22, which dope inthe liquid state, will permeate Y the fabric 22 and when dried bond thesame to the fastening strip I6. The metal strip I6 will .prevent thedope frornseeping through to wet the upper surface of the foundationstrip I4. Thu-s,V in the finally assembled condition, the cover fabric22 is connected to the foundation strip I4 through the fastening stripI8 and is free to move about the threads 20 and is not fastened downwith respect to the Iouter edges of the fianges I2.

In Fig. 2, the structure disclosed above is shown in an explodedarrangement with the web I and flanges I2 removed. The fabric 22 isshown as extending outwardly and upwardly from its center portion Whereit is doped. Such a condition results when aerodynamic forces act uponthe part of the craft so covered. The method of fastening the strip I8by stitches 20 through the vimpermeable strip I6 and the foundationstrip I4 is clearly shown in this gure.

In Fig. 3, that form of the invention shown in Fig. l is shown in aposition that it will take under the action of aerodynamic forcestending to lift the cover 22. At such time, the fastening strip I8 willrise with the cover 22 because it is bonded thereto by the dope, or thelike. The stitches 29 thus transfer the tension created by the forceslifting the cover 22 in a straight line to the foundation strip I4 whichcan move up and away from the upper surface of the flange I2. Thus, thetension upon the cover 22, produced by the forces lifting the same, istaken in shear by the dope between the fastening strip I3 and the cover22, and between threads 20, and is transferred in a straight line to thefoundation strip I4 which bears upon the left hand side of flange I2 inthe case shown in Fig. 3. It will be understood that as the left handside of cover 22 is lifted due to aerodynamic action, the oppositecondition will obtain and the right hand flange I2 will assume theforces. Inasmuch as the two flanges I2 are assembled with the web I0 toform a portion of an I section, for example, there will be an increasedresistance to Vbending in a transverse direction inasmuch as the stripI4 for fastening the cover 22 to the rib of the section will alsostrengthen the rib.

In many places the weight can be reduced substantially from the Weightof prior art structure While retaining full strength for the parts.

vIn assembling that form of the invention shown in Figs. 1, 2 and 3, thefoundation strip I4, the impermeable strip or wax coat or the like I6may be applied to the central portion of the foundation strip I4, thefastening strip I8 can be laid over the portion I6, and the entirestruci ture can be stitched together by the stitches 20 upon a machine,thus eliminating a great number of hitherto performed manual operations.The assembled structure can then be applied to the web I0 and theflanges I2, the lower portions of the foundation strip I4 wrapped aroundand sewed or cemented to,y the web I0 and the under surfaces of theflanges I2. Such operations facilitate mass production and eliminate theneed for highly skilled help in nally assembling the cover 22 to the ribsection.

The subassembled part described above can be placed upon wing beams,spars, ribs and other structural parts of the Wing as well as upon thefuselage framing members and upon control surface parts. Many of thesesubassembled parts may then be made relatively small and easy to handleand the separate parts of the air frame can have securing means such asdescribed above placed upon them before these parts are finallyassembled together to complete the air frame. After the air frameisassembled with the fastening parts in plaoe,.the cover 22 for theWing, or fuselage, or the like can be slipped over the part and doped,in place. This method of construction vvillfacilitate rapid productionand 0bviously eliminate a large number of hereto performed steps inassembling the .covers of air- .craft parts by the stitching methods orthe methods of glueing down the cover upon structural parts.

Inasmuch as the instant structure gives flexibility throughl 4thesecuring strips YI3 and the cover 22 throughv the stitches 20, the cover22 will not have -a tendency to peel off of the part to which it isdoped, which is a distinct advantage over directly doped on covers, forexample. l Y

l The structuredescribed above also adds to the strength and toughness'of an assembled part. The foundation strip I4, in combinationwith theflanges I2, secured to web portions, provides structural parts in thefinal assembled state that exert additional resistance to transversebending, and even when bent have a toughness which prevents fracture ofthe structural part because the foundation web I4 will assume tensilestresses that otherwise would have to be taken in toto by the anges I2or the web I II of the aircraft section. y

In Figs. 4 and 5, a modified construction is shown, in the static state,in Fig. 4, and under aerodynamic action in Fig. A5. A web 30 has flanges32 around which a foundation strip may be wrapped and glued and/or sewnin place. The anges 32 have upper surfaces 34 which slope down from thecenter portion of the entire structure which provides a groove 36 inwhich the stitches for the securing strip 38 may lie. As best shown inFig. 5, when the fabric 40 is moved upwardly by aerodynamic forces, thetension in the strip may be taken in alignment with the sloped surfaces34 of a flange 32 and the foundation strip will not be urged away fromthe surface 34.

In Fig. 6, a further modified structurels shown wherein the foundationstrip 50 is secured to the web 52 by stitches 54 as well as by dope. Thefoundation strip 50 overlies and is arranged at an angle VWith anges l56to brace the same for rotation around the Web 52 to thus strengthen thestructure and avoid the need for heavy parts making up the fianges 56and the web 52 for resisting torsional moments exerted by the coverfabric.

In Fig. 7, a further modified structure is shown wherein la foundation`*sifrip Gillis .secured to upper surfaces 62 of flanges'. Thefoundation streng-th nor absorb'large forces. The Vbalance of theconstruction 4for securing lthe coverinplace is` the "same as describedin connection with 'the other modifications, and will resist peeling offby taking stresses -in shear. Y

While I have shown anddescribed severalgforms that Lmy linventionmay-take,`A and fhaveexplained :the method for securing `afcoverftoanvairrfframe part in an improved manner for providing a smooth exteriorsurface and for strengthening the part covered, it will be understoodthat still other forms and modifications and modied steps in the methodwill occur to those skilled in the art. For these reasons, I wish not tobe limited in my invention only to those forms and methods shown anddescribed but by the scope of the following claims.

I claim:

1. In aircraft, in combination, a structural part, a foundation stripsecured to said part, a fastening strip secured by stitches to saidfoundation strip and having flaps at opposite sides of the stitches,impermeable means between said foundation strip and said flaps, a smoothcover fabric lying upon said fastening strip, and means bonding saidfabric to said fiaps.

2. In aircraft, in combination, a structural part, having a groovedsurface, a foundation strip secured to said part, a fastening stripsecured by stitches to said foundation strip and having aps at oppositesides of the stitches, said stitches lying in the groove in saidsurface, impermeable means between said foundation strip and said fiaps,a smooth cover fabric lying upon said fastening strip, and means bondingsaid fabric to said flaps.

3. In aircraft, means for securing a cover fabric to a structural membercomprising, in combination, a flanged portion on said structural memberhaving a longitudinally extending groove therein, a foundation stripoverlying said flange and secured to said member, a fastening stripsewed to said foundation strip with the stitches lying in said groove,impermeable means between said fastening strip and said foundationstrip, a cover fabric lying upon said fastening strip, and a bondingagent securing said fabric to said fastening strip.

4. In aircraft, means for securing a cover fabric to a structural membercomprising, in combination, a portion on said structural member having alongitudinally extending groove therein, a foundation strip adjacentsaid portion and secured to said member, a metal foil strip, a fasteningstrip sewed through said metal foil strip to said foundation strip withthe stitches lying in said groove, a cover fabric lying upon saidfastening strip, and a bonding agent securing said fabric to saidfastening strip.

5. In aircraft, means for securing a cover fabric to a structural membercomprising, in combination, a portion on said structural member having alongitudinally extending groove therein, a foundation strip adjacentsaid portion and secured to said member, an impermeable strip, afastening strip sewed through said impermeable strip to said foundationstrip with the stitches `.iyi-*rigilmisaidx'groove, fa Yfccrv'er tabriclying upon .saidzifastening strip, fand a bondin'g agent-'secur-.Lfingssaidifabricltosaidiastenng f6. In aircraft-- means .forse'curin'gia cover ifab'- nel -to 1a structural :member: comprising; finfreembination,-- a ianged` iportionhfon said-structural':memberlnavingfafidngitudinanyextendingrgwove -therfein afoundationstrip s overlying saidfflange sa' d secured `to saidmeister,-portions=f--xsaid strip being '-.arrarfgedvat 1 an angle to fthe ridgespf said Flarig'edlportio'n andfse'cured `to lsaid member Ito strengthen-'th'elistructure fastening i"s'trp vsewed-to isa'id foundation Estr-ipth -thelistitches @lying --=s`a'id=groove, impermeable lmeans betweensaid fasteningy strip' and said 'ffourfdationfstrip ifa`cover'fiabric'lyingfupon said fastening strip, and a bonding agentsecuring said fabric to said fastening strip.

Y f7. ,Int aircraft. means Yfor securing cover f-fabric to a foundationmember, comprising infcombinaftion, a fastening strip, means securingsaid fastening strip to said foundation member to provide asubstantially smooth surface for said fastening strip, impermeable meansbetween said fastening strip and said member, a cover upon saidfastening strip, and a bonding agent securing said cover fabric to saidfastening strip.

8. In aircraft, means for securing cover fabric s to a foundation memberhaving a flange, comprising in combination, a fastening strip, meanssecuring said fastening strip to said flange to provide a substantiallysmooth surface for said fastening strip, portions of said strip beingarranged to strengthen said member, impermeable means between saidfastening strip and said member, a cover upon said fastening strip, anda bonding agent securing said cover fabric to said fastening strip.

9. In aircraft, in combination, a structural part, a foundation stripsecured to said part, a fastening strip secured by stitches to saidfoundation strip and having flaps at opposite sides of the stitches, asmooth cover fabric lying upon said fastening strip, and means bondingsaid fabric to said aps.

10. In aircraft, means for securing a cover fabric to a structuralmember having a longitudinally extending groove therein, a foundationstrip secured to said member and overlying said grOOve, a fasteningstrip sewed to said foundation strip along said groove with the stitcheslying in said groove, a cover fabric overlying said fastening strip andsaid stitches, and means for adhesively securing said fabric to saidfasteningstrip.

11. In aircraft, in combination, a structuralV part, a foundation stripsecured to said part, a fastening strip secured to said foundation stripand having iiaps extending transversely of the foundation member, asmooth cover fabric overlying said fastening strip and said stitches,and

means for adhesively securing said fabric to said iiaps.

12. The method of securing a cover fabric to an underlying structuralmember which comprises the steps of securing a fabric foundation stripto the structural member, placing a fastening strip of permeablematerial over said foundation strip with a strip of fluid impermeablematerial therebetween, securing said strips together in the aforesaidrelation by stitching, placing the cover fabric over said fasteningstrip, and adhesively bonding said cover fabric to said fastening stripby impregnating said cover fabric and said fastening strip in thevicinity of said stitching with an adhesive.

.fastening and foundation strips, placing said cover fabric upon saidfastening strip, and applying an adhesive adjacent said stitching thatwill vpermeate both said cover fabric and said fastening strip tothereby secure the two in such manner that shear forces applied to saidcover fabric are taken in shear by the adhesive.

WALTER W. LYSAK.

REFERENCES CITED The following references are of record in the le ofthis patent: 1 Y

Number Number 15 438,327 28,701

8 UNITED STATES PATENTS Name Date Hooper Feb. 17, 1920 Henderson Dec.14, 1926 Loetscher Nov. 15, 1932 Bellanca Mar. 21, 1933 Sobie June 23,1936 Robinson Sept. 1, 1936 Schmidt July 18, 1939 Woodall et al Aug; 4,1942 Marschner et al. May 16, 1944 FOREIGN PATENTS Country Date GreatBritain Nov. 14, 1935 Great Britain 1913

